An image processing device includes a first encoding processing portion to perform first encoding processing according to a first compression method for compressing multilevel image data and a second encoding processing portion to perform second encoding processing according to a second compression method for compressing binary image data. A determination portion determines whether an image made up of acquired image data is a monochrome image. A data volume estimating portion makes an estimation between a first data volume when image data forming the monochrome image is compressed by the first encoding processing and a second data volume when the image data is compressed by the second encoding processing as to which data volume becomes smaller. A file creating portion creates a data file from image data that has the smaller volume.